Józef Śleziona

Influence of Al–Al2O3 composite powder on the matrix microstructure in composite casts

Abstract The structural characterization is presented of composite casts with an AlMg4 alloy matrix, with the composite powder (Al–Al2O3)cp reinforcement obtained in a rotary-vibration mill. On the cross-sections of ingots, metallographic specimens have been made and, by means of quantitative metallographic methods, the grain size distributions have been determined. Statistical tests of the results obtained from the grain plane section area measurements have been performed. An influence has been found of the (Al–Al2O3)cp composite powder on the matrix grain size distribution, depending on the distribution of the composite powder particles in the ingot, whereas no influence of (Al–Al2O3)cp on the mean grain size of the AlMg4 alloy has been found.

Characterisation of CF/AL-MMC Manufactured by Means of Gas Pressure Infiltration

Constantly rising demands on extremely stressed lightweight structures, particularly in traffic engineering as well as in machine building and plant engineering, increasingly require the use of continuous fibre-reinforced composite materials. Due to their selectively adaptable characteristics profiles, they are clearly superior to conventional monolithic materials. Composites with textile reinforcement offer the highest flexibility for adaptation to reinforcing structures in to complex loading conditions. This study shows that the gas pressure infiltration technique was successfully assessed for manufacture of carbon fibre reinforced aluminium metal composites (CF/Al-MMCs), consisting of unidirectional as well as bidirectional Ni-coated carbon fibres with different Al-alloy matrix systems. As wail as investigating of the deformation and failure behaviour of CF/Al-MMCs, their thermo-physical properties, were determined such as the coefficient of thermal expansion. Furthermore, fractographic analysis and closer microscopic inspections indicate they fail with a brittle fracture.

Mechanical Properties of Aluminium Matrix Composites Reinforced with Glassy Carbon Particles

The mechanical properties of composite materials with glassy carbon (GC) have been presented. The effect of size and reinforcement value on tensile strength, impact and tribological characteristics (coefficient of friction and wear) were estimated. It has been found that the reinforcement value decide on mechanical properties. Enlargement of particles value leads to decreasing of tensile strength and impact strength. It has been shown that particle size has small influence on studied properties. Destruction energy for the composites with particles exceeding 100 µm is similar. The measurement of coefficient of friction proved, that increase of reinforcement value leads to decreasing of coefficient of friction from 0.4 for 5% value to about 0.12 for 20% of particle value. The coefficient of friction is comparable for the composites containing particles of 200 µm size and is less dependent on reinforcement value. However size of the particles decide on the character of coefficient of friction changes.